Flashing lamp circuit using a transistor oscillator



Nov. 26, 1968 H. ALEEDER, JR

FLASHING LAMP CIRCUIT USING A TRANSISTOR OSCILLATOR Filed Feb. 18, 1966 3 Sheets-Sheet 1 INVNTOK HARRY A. LEEDER JR. By B'WMM Nov. 26, 1968 A. LEEDER, JR

FLASHING LAMP CIRCUIT USING A TRANSISTOR OSCILLATOR 5 Sheets$heet 2 Filed Feb. 18, 1966 LPL RP RPL m/vE/vToIL HARRY A. LEEDER JR. 3 6m man Nov. 26, 1968 H. A. LEEDER, JR

Filed Feb. 18. 1966 5 Sheets-Sheet (5 EP] b/ we c.

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United States Patent 3,413,519 FLASHING LAMP CIRCUIT USING A TRANSISTOR OSCILLATOR Harry A. Leeder, Jr., Skaneateles, N.Y., assignor to R. E. Dietz Company, Syracuse, N.Y., a corporation of New York Filed Feb. 18, 1966, Ser. No. 528,499 15 Claims. (Cl. 3152tl9) This invention relates generally to electrical signal generators or oscillator circuits and relates more particularly to such a circuit having a semi-conductor device used in conjunction with a relay for switching relatively heavy loads. The invention is an improvement on Patent 3,113,242 issued Dec. 3, 1963, to the same inventor and provides means in such a circuit for operating flashing turn signal lights, alternately flashing signal lights, and emergency signal lights, together with indicator pilot lights which can indicate lamp outages.

The circuit of the invention is particularly adapted for use in flashing automotive vehicle signal lights in which multilamp and comparatively heavy signal loads are flashed singly, alternately, or together. By providing suitable selective switching arrangements the circuit is adapted for use in a variety of systems.

In one switching system provision is made for selectively flashing right or left turn signal lamp loads and provision is also made for flashing all lamp loads as an emergency signal. In another system provision is made for an alternately flashing lamp turn or stop signal and also for an emergency signal in which all the lamps are flashed together. In still another system provision is made for a flashing lamp turn signal, an alternately flashing lamp signal, and an emergency signal in which all lamps are flashed on and off together. In each system provision is made for a pilot light flash indicator which may be made to indicate lamp outage as well.

By a simple adjustment the circuit is equally effective whether the vehicle has a negative ground or positive ground battery, and the circuit provides a uniform flash rate over a great range of operating voltage and temperature.

The principal object of the invention is to provide a transistorized signal lamp flasher circuit having a uniform flash rate which may be utilized in a number of flash signal systems.

Another important object is to provide pilot lamp indicating means in such a system, the pilot lamp indicating operation of the turn signal and also indicating lamp outage.

A further object is to provide a versatile oscillator circuit for use with multilamp loads in which the number of lamps may be of any practicable chosen number with lamp outage indication for the chosen load.

A still further object is to provide a lamp flasher circuit providing the capability for alternate flashing as well as normal flashing.

Other objects and advantages will become apparent from the following description in conjunction with the accompanying drawings, in which:

FIGURE 1 is a schematic circuit diagram of the oscillator circuit of the present invention arranged in a system having a positive ground and providing for flashing turn signals with pilot light indicator means and overriding emergency flash signal, the oscillator circuit being enclosed in the broken line rectangle;

FIGURE 2 is a similar diagram showing the circuit arranged in a system providing for an alternating flashing normal signal with pilot indicator means and an overriding emergency flash signal, the details of the oscillator circuit being omitted;

FIGURE 3 is a diagram similar to FIGURE 1 with the oscillator circuit shown in the broken line rectangle and arranged for a negative ground system; and

FIGURE 4 is a diagram similar to FIGURE 2 showing a system providing for flashing turn signals with pilot light indicator means, an overriding alternating flash signal, and an overriding emergency flash signal.

With reference to FIGURE l, the flasher circuit 10 is shown within a broken line rectangle 11 representing a flasher box or container with terminals X, L, Gnd; P, and L. The flasher circuit is provided with a source of direct current 12, shown as positive grounded, and wired in series through a control or ignition switch 13 to the terminal X.

Within the rectangle 11 the terminal X is wired as shown through the interconnected terminals 14 and 15 to a reference point 16 and thence to the collector terminal C of PNP transistor 17. Reference point 16 is also connected through a first resistor R1, a second resistor R2 and a capacitor 18 to one terminal 19 of the coil of a timing relay 20, the other terminal 21 of the coil being connected to the emitter terminal E of transistor 17.

The junction 22 of the resistor R2 and capacitor 18 is connected to the base electrode B of transistor 17, and the junction 23 of resistor R1 and resistor R2 is connected to the armature contact 24 of a normally open first set of contacts 24-25 on the relay 20. Contact 25 is connected to terminal 19 of the relay coil and also, through the interconnected terminals 26 and 27, to contact 28 of a second set of make-before-break contacts 28-29-30 on the relay 20. Contact 30 is connected to the grounded terminal Gnd.

There is a third set 313233 of contacts on relay 20 arranged as a single pole, double throw switch, contact 32 being normally in contact with contact 33 but, upon operation of the relay, arranged to break contact with 33 and swing into contact with contact 31. Contact 32 is wired in series with terminal X through the coil 35 of a pilot indicator relay as shown. Contact 33 is connected to the terminal L and contact 31 is connected to contact 29 of the second set of contacts and to the terminal L.

Terminal 28 of the second set of contacts is arranged, to first make contact with terminal 30 and then to break from contact 29, with which it is normally closed, during the time that the relay armature of the coil 20 is pulling in and before contact 32 closes to contact 31. When the relay 20 is fully operated contacts 28 and 30 are closed and contacts 28 and 29 are open.

A pair of normally open contacts 36-37 on the pilot indicator relay are arranged to close when the current load through the coil 35 operates the relay. Contact 36 is connected to the terminal X and contact 37 is connected to the terminal P, as shown.

It will be understood that the terminals X, L, Gnd, P.

and L may be connected in the vehicle wiring in a variety of combinations according to the signal switching arrangement desired. In the arrangement of FIGURE 1 the terminal L is not used. Terminal P is connected to one pole 40 of a double pole double throw turn signal switch 40-41, the other pole 41 being connected to the terminal L. Pole 40 may be moved, as desired, into contact with switch contact PL or PR, PL being connected through left turn pilot lamp 42 to ground, and PR being connected through a right turn pilot lamp 43 to ground. Similarly, pole 41 is simultaneously engageable with switch contact SL or SR. S1 is connected through front and rear left turn signal lamp loads 44 and 45, respectively, to ground. SR is connected to front and rear right turn signal lamp loads 46 and 47, respectively, to ground.

There is also an overriding double pole single throw emergency switch 48-49, both pole 48 and pole 49 being connected to terminal L. Contact EL of switch 48-49 is connected through both left turn signal lamp loads 44 and 45 to ground and contact ER is connected through both right turn signal lamp loads 46 and 47 to ground.

It will be understood that the left turn signal load 44- 45 and the right turn signal load are each a multilamp load having a specified number of lamps, usually from 2 to 7 or 8 lamps in each load. The pilot indicator relay coil 35 is adjusted (by using a wire of chosen gauge and chosen number of turns) to pull in for the specified number of lamps in the load and not to pull in when the number of lamps is one less so that each pilot light serves as a flash indicator and also as a lamp outage indicator.

In operation, the oscillator circuit shown in the broken line rectangle, together with the switch arrangement of FIGURE 1, functions as follows:

When the control switch or ignition switch 13 is closed, operating current for the timing circuit enters via terminal X from the battery 12, flows through the timing circuit and relay and leaves from the coil terminal 19 via contacts 28 and 29 to terminal L. If turn switch 40-41 and emergency switch 48-49 are off, there is no connection to ground so that the timing circuit does not function. When either the turn switch or emergency switch is closed a connection through one or both of the signal lamp loads is made to ground and the timing circuit begins to operate. Current flows from collector C, through the transistor and from emitter E through the relay coil 20 to ground. Battery voltage is applied to base B of the transistor through resistors R1 and R2. Capacitor 18 begins to charge and the voltage differential between the base of the transistor and terminal 19 begins to increase.

Voltage between the emitter E of the transistor and terminal 19 equals the base voltage less the transistor base-emitter voltage drop and, as the voltage at base B rises the voltage across relay 20 rises also. As more fully explained in Patent 3,113,242, when the voltage across relay 20 reaches the operating or pull-in voltage of the relay, the relay operates and the first phase of operation is completed.

During the second phase the junction point 23 is connected to terminal 19 through relay contacts 24 and 25 and capacitor 18 begins to discharge through resistor R2 and contacts 24 and 25. The voltage at the base B of the transistor falls and the voltage at the emitter E of the transistor follows the base voltage down.

When the voltage across relay 20 reaches the release or drop out voltage of the relay, contact 24 opens from contact 25 and all contacts on the relay 20 return to the positions shown in FIGURE 1.

When relay 20 is in its normal position contact 32 is connected through contact 33 with the terminal L but L is unconnected to ground so no current is applied to the pilot indicator relay 35.

When relay 20 pulls in, however, contact 32 engages contact 31 and a circuit is set up through terminal L to ground through one or more of the signal lamp loads. If turn signal switch 40-41 has been operated for a left turn, for example, terminal L is connected to ground through the left turn signal lamp loads 44 and 45 and the lamps flash on.

As current flows through relay 35 contact 36 closes to contact 37 and a circuit across the source 12 is set up through terminal P, contacts 40 and PL and through pilot lamp 42. As explained above, if one of the lamps of the signal lamp load 44-45 is out, current through relay 35 is insufficient to operate the closing of contact 36 and pilot lamp 42 will not light up.

Should the turn signal switch be operated for a right turn, of course, signal lamp loads 46 and 47 will be illuminated, along with pilot lamp 43.

Should emergency switch 48-49 be operated a circuit is set up through the closed contacts 48-EL through left turn signal load 44-45 and simultaneously through closed 4 contacts 49-ER to the right turn signal lamp load 46-47 and all signal lamps will flash on. Contact 40 on the turn signal switch not being closed, neither of the pilot lamps will operate.

As long as the turn switch 40-41 or the emergency switch 48-49 remains closed timing relay 20 pulls in and drops out as the circuit 10 oscillates with the voltage across the relay oscillating between the values required for pull-in and drop out.

The above description assumes that the oscillating circuit is continuously connected to ground through the contact 28 of the set of make-before-break contacts 28-29- 30. Contact 28 is normally closed with contact 29 which is connected through terminal L through switches 40-41 and 48-49 and thence through the signal lamp loads to ground. No current will flow through the circuit 10, therefore, until the turn switch or emergency switch is operated.

In order to prevent too rapid drop in the voltage differential between reference point 16 and terminal 19 in the emitter follower circuit, which would be the case if contacts 28 and 29 were to remain closed when relay 20 pulls in and closes contact 32 with contact 31, the operation of relay 20 breaks the contact between contacts 28 and 29 and establishes a circuit direct to ground through the contact 30 and the Gnd terminal. To provide continuity in the ground return from the oscillator circuit, contact 30 is arranged to engage contact 28 before the latter contact breaks from contact 29, and the break between contacts 28 and 29 takes place before the engagement between contacts 31 and 32.

The relay used in the oscillator circuit 10 requires careful design because it is an integral part of the circuit, and the performance characteristics of the relay directly atfect the timing stability of the oscillator circuit.

When the circuit is oscillating the voltage across the coil of relay 20 oscillates between the pull-in and drop-out voltages, which are fixed by the design, as shown in FIG- URE 5 points a, b and c. The section a-b is a portion of an exponential curve a-b-d which has the voltage e as an upper asymptote. Voltage e is a portion of the battery voltage E determined bly resistors R and R the parameters of transistor 17, and the resistance of the coil of relay 20. The discharge section 11-0 is a portion of the exponential curve b-c-e which has the voltage e as a lower asymptote. Voltage e is determined by the transistor leakage current fiowing through the relay coil.

In an automotive installation the battery voltage varies over a rather large range; for the typical 12 volt system the range is 11 to 15 volts. FIGURE 5 has been drawn to represent the high voltage condition. FIGURE 6, in the curve a-b'c', shows the efiect of low battery voltage on the charging time, and also shows the elfect of increased transistor leakage current on the discharge time. To minimize the effects of these voltage changes, it is necessary to control the pull-in and drop-out voltages within narrow ranges to obtain optimum results.

In FIGURES 5 and 6 EPI is the pull-in voltage of the relay and deter-mines the location of points b and b. BBC is the drop-out voltage of the relay determining the location of the points a and c, and a and c. TC and TC represent the charging time, the relay being in non-actuated state. TD and TD represent the discharge time of the circuit, the relay being in actuated state, T in FIG- URE 5 represents the time lapse during high voltage conditions for one cycle of the oscillator circuit and T indicates the time lapse for one cycle during low battery voltage conditions.

By assigning the proper values to EPI and EDO relative to the supply voltage E the variation in the charging time and discharging time can be held to a minimum as voltage E varies.

To keep the relay operating voltages within the desired limits it is necessary to control the mechanical spring and contact forces, and the number of turns and resistance of the coil. Design values for a 12 volt relay in a constructed embodiment of the invention were:

Referring now to FIGURE 2, the oscillator circuit 10, represented by the broken line rectangle 11 in this figure, may be arranged in a switching system providing for an alternately flashing warning signal and an emergency signal in which all the signal lamps flash together.

Terminal L' is connected through the normally closed pole 50 and contact 55 of a triple pole single throw emergency switch 50-51-52 to one pole 53 of a double pole single throw turn signal switch 53-54. Pole 53 is movable upon operation of the switch to close to contact 57 which is connected through a multilamp signal lamp load 59 on one side of the vehicle to ground.

Terminal L is connected to the normally open pole 54 of the switch 53-54 and pole 54 is adapted to close upon operation of the switch to a contact 60. Contact 60 is connected through another lamp load 59 on the other side of the vehicle to ground.

Terminal P is connected through a pilot lamp 64 to ground.

The overriding emergency switch 50-51-52 has its other two poles 51 and 52 each connected to Terminal L. Poles 51 and 52 are normally open but are provided with contacts 66 and 67, respectively. Contact 66 is connected through lamp load 59 to ground and contact 67 through lamp load 58 to ground, as shown.

The operation of circuit is the same as that described in connection with FIGURE 1 except that terminal L in this arrangement may be connected through a lamp load to ground.

When switch 53-54 is operated to bring its poles in contact with contacts 57 and 60, respectively, for example, terminal L is connected through pole 54 and its contact 60 to signal lamp load 58 and thence to ground, and current begins to flow through the oscillator circuit. Simultaneously, terminal L is connected through pole 53 and its contact 57 to load 59 and thence to ground.

Since contact 32 is normally engaged with contact 33 (FIG. 1) a circuit is immediately established across the source through the lamp load 59 and its lamps flash on until relay 20 pulls in and the connection is broken through contacts 32 and 33, When contact 32 engages contact 31 a circuit across the source is set up through terminal L, pole 54, and its contact 60, through load 58 and the lamps of this load flash on until relay 20 drops out. An alternately flashing lamp signal is thus obtained.

Since terminal P is connected through pilot lamp 64 it flashes each time contacts 36 and 37 of relay 35 close upon operation of the relay.

When the overriding emergency switch 50-51-52 is operated, normally closed pole 50 is opened breaking the connection from the alternate flasher terminal L to pole 53 of the other switch. Pole 51 closes to its contact 66 and pole 52 to its contact 67. Each time contact 32 closes to contact 31 on operation of relay 20, therefore, both loads 59 and 58 flash on to give the emergency signal of all signal loads flashing.

The oscillator circuit 10, may be adapted for use in vehicles having a negative ground wiring system. The oscillator circuit 10', shown in FIGURE 3, is exactly the same as the circuit 10 in FIGURE 1 except that terminal 14, instead of being connected to terminal 15, is connected to terminal 26, and terminal 27, instead of being connected to terminal 26, is connected to terminal 15. The

power source 12 has its negative side grounded and thus connected to the Gnd terminal and to pilot lamps 42 and 43 and to loads 44, 45, 46, and 47. The positive side is connected to terminal X but, because of the simple readjustment of internal terminals 14, 15, 26 and 27, the X terminal is connected to coil terminal 19, and contact 28 is connected to reference point 16. The other connections and the switching arrangement and operation is the same as in FIGURE 1.

Reversal of the battery polarity can be accommodated in the same manner in the other modifications of switching arrangements shown herein. It should also be noted that this reversal of polarity may also be accomplished by the substitution of an NPN transistor for the PNP transistor 17 of FIGURE 1.

Referring now to FIGURE 4, a switching arrangement is shown in connection with the oscillator circuit 10, represented by the broken line rectangle 11, for providing for a left or right flashing turn signal, an alternately flashing warning signal, and an emergency signal in which all the signal lamps are simultaneously flashed on and off.

A double pole, double throw turn signal switch 70-71 has its pole povided with alternative contacts L" and R" and its pole 71 provided with alternative contacts LP and RP. Contact L" is connected to ground through a front left turn signal lamp load 72 and a rear left turn signal lamp load 73. Contact R" is connected to ground through a front right turn signal lamp load 74 and a rear right turn signal lamp load 75, as shown.

Switch pole 70 is connected through a normally closed contact 76' and the pole 76 of a double pole single throw alternate flash signal switch 76-77 to the terminal L. Pole 71 is connected to the terminal P and its contacts LP and RP are connected respectively through pilot lamps LPL and RPL to ground.

Pole 76 of the alternate switch 76-77 is provided also With a contact 78 connected through loads 74 and to ground, and the other pole 77 is provided with a contact 79 connected through loads 72 and 73 to ground. Pole 77 is connected through a normally closed contact 80' and pole 80 of a triple pole, single throw emergency switch 80-81-82 to the terminal L of the flasher box 11.

Pole 81 of switch 80-81-82 is normally open but is provided with a contact 84 connected to ground through loads 72 and 73. Pole 82 of the emergency switch is also normally open and is provided with a contact 85 connected to ground through loads 74 and 75. Poles 81 and 82 are both connected to terminal L of the box 11. Terminals X and Grid are connected externally of the box as described in connection with FIGURE 1.

When turn signal switch 70-71 is moved to signal a left turn, for example, the pole 70, in engagement with contact L" connects left turn loads 72 and 73, through the normally closed pole 76, to terminal L. In the opera tion of circuit 10, as described in connection with FIG- URE 1, when contact 32 engages contact 31, the left turn signal loads are thereby flashed on and off in accordance with the operation of relay 20. Similarly, right turn loads are flashed on and off when the pole 70 engages the contact R".

Since pole 71 of the turn switch is connected to terminal P the left or right pilot lamps LPL or LPR are illuminated when their corresponding signal lamp loads flash on.

When the alternate flash switch 76-77 is operated, pole 77, connected to terminal L, engages contact 79 and flashes loads 72 and 73 because of the normal engagement of contacts 32 and 33 in circuit 10.

When the operation of the timing relay 20 breaks this engagement and connects contacts 31 and 32, the lamp flashing circuit is connected through terminal L, now closed contacts 76 and 78 and through loads 74 and 75 to ground. Left and right turn signal lamps thereby flash alternately until switch 76-77 is released.

When emergency switch 8081-8-2 is operated, the pole 80 breaks all connections between terminal L and the lamp loads, and poles 81 and 82 of the switch connect the terminal L to ground through loads 72, 73, 74 and 75 causing all signal lamps to flash on each time the pull in of relay 20 causes the engagement of contacts 31 and 32.

From the foregoing it will be apparent that the oscillator provides a versatile flasher device which may be utilized in a variety of switching arrangements. By providing a combined transistor and relay operated flasher, a comparatively heavy signal lamp load current may be flashed on and off by a comparatively small current in the base circuit of the transistor.

By providing three sets of contacts on the timing relay 20 provision may be made for alternating right and left flashing lamps, coil characteristics, spring tensions, and resistances can be more closely controlled for a uniform flash rate, the timing circuit may be completely disconnected until a signal switch is closed, and provision may be made for an indicator pilot signal for each lamp load. By adjusting the pilot indicator relay the pilot lamps may also be made to indicate lamp outages.

As will be apparent to those familiar with the art, the invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The embodiments disclosed therefore are to be considered in all respects as illustrative rather than restrictive, the scope of the invention being indicated by the appended claims.

What is claimed is:

1. A lamp flasher and outage indicator circuit comprising: a source of direct current having one side connected to ground; a transistor oscillator having a voltage build-up circuit including the collector and emitter electrodes of a transistor and a timing relay coil connected in that order to the source and through a return switching circuit to ground; the oscillator having a charging circuit including first resistance means, second resistance means, and a capacitor connected in series across the transistor and coil, the junction point of the second resistance means and capacitor being connected to the base electrode of the transistor; the timing relay having a first set of normally open contacts adapted to close upon the operation of the relay to connect the junction point of the first and second resistance means to the ground return circuit; and a second set of double throw load switching contacts on the timing relay adapted to switch signal lamp loads across the source alternately through a first selected lamp load and then through a second selected lamp load for alternating flashing of the loads.

2. The circuit defined in claim 1 having a third set of make before break contacts arranged in the oscillator ground return circuits to normally connect the relay coil to the grounded side of the source through a turn switch and lamp load and to transfer said ground return directly to ground during the interval when the timing relay armature is closing and before the pole of the load switching contact set moves from its normally open contact to its normally closed contact to maintain the continuity of current flow, whereby the oscillator is inoperative until a load is selected by means of the turn switch.

3. The circuit defined in claim 2 having at least one pilot lamp and having the coil of a pilot lamp relay included in the signal lamp operating circuit between the source and the second set of contacts, and an indicating circuit connected across the source comprising a pilot lamp and a pair of pilot lamp relay contacts in series arranged for opening or closing upon operation of the pilot lamp trelay, whereby the pilot lamp indicates the chosen load is flashing.

4. The circuit defined in claim 3 characterized by each lamp load having a chosen number of lamps and the pilot lamp relay coil being adjusted to be operative with a load equal to or greater than the chosen number of lamps and to be inoperative with a load of one less than the chosen number of lamps, whereby the pilot lamp indicates load lamp outage.

5. A lamp flasher and outage indicator circuit comprising: a transistor oscillator including a source of direct current grounded on one side and a switch in series; a transistor connected as an emitter follower with a timing relay coil in the emitter circuit; a charging circuit consisting of a first resistor, connected to the transistor collector electrode, a second resistor, and a capacitor in series connected across the transistor and relay coil, the junction of the second resistor and capacitor being connected to the base of the transistor, the junction of the first and second resistors being connected by a first set of normally open contacts on the timing relay to the junction of the coil and the capacitor, said last mentioned junction being the ground return point for the timing circuit; a plurality of signal lamp loads; a second set of make before break contacts on the timing relay arranged to normally connect the relay coil to the grounded side of the source through a chosen load and to transfer the ground return point of the timing circuit directly to ground during the interval when the timing relay armature is closing to maintain the continuity of current flow; a load circuit including the coil of a pilot lamp relay connected across the source and switch alternatively by means of a third set of single pole double throw timing relay contacts, which are connected respectively to ground through a normal load and an alternate load and an indicating circuit across the source and switch through a normally open pair of contacts on the pilot indicator relay and a pilot lamp, the pilot indicator relay being adjusted to indicate the failure of one or more of the load lamps.

6. In an electronic switching circuit: a source of direct current grounded at one side; a plurality of signal lamp loads; a timing relay having a first set of normally open contacts, a second set of load switching contacts, and a third set of make before break contacts, the first set arrange-d to close upon pull-in of the relay, the second set arranged to switch upon pull-in of the relay from an alternate flash contact to a flasher contact, and the third set arranged to switch during operation of the relay to a grounded contact before breaking from its normally closed contact, the latter contact being grounded through a selected load; a relay operating circuit including the collector and emitter electrodes of a transistor and the relay coil being connected in that order across the source through the third set of contacts; a charging circuit including first resistance means, second resistance means, and a capacitor connected in series in that order from the transistor collector electrode across the transistor and relay coil, the junction point of the second resistance means and capacitor being connected to the base electrode of the transistor; 21 load circuit including the coil of a pilot lamp relay connected through the second set of timing relay contacts and selected grounded signal lamp loads across the source; the first set of timing contacts being adapted to connect the junction of the first and second resistance means of the charging circuit to ground through the third set of timing relay contacts to provide a dropout circuit for the relay; and the second set of timing relay contacts being adapted to switch the load circuit from one signal iamp load to another; and an indicator lamp circuit comprising an indicator lamp and a normally open pair of contacts on the pilot lamp relay to complete the indicator lamp circuit across the source when current of a chosen amount is flowing in the load circuit.

7. The circuit defined in claim 6 characterized by the timing relay being adapted to pull in at a voltage within forty-six to fifty-four percent of the nominal voltage of the current source and adapted to drop out at a voltage within ten to nineteen percent of said nominal voltage.

8. A lamp flasher and outage indicator circuit comprising: a transistor oscillator including a source of direct current and a switch in series; a transistor connected as an emitter follower with a timing relay coil in the emitter circuit; a charging circuit consisting of a first resistor connected to the transistor collector electrode, a second resistor, and a capacitor in series in that order connected across the transistor and relay coil, the junction of the second resistor and capacitor being connected to the base of the transistor, the junction of the first and second resistors being connected by a first set of normally open contacts on the timing relay to the junction of the relay coil and capacitor; a plurality of lamp loads; a second set of make before break contacts on the timing relay arranged to normally connect the relay coil to the grounded side of the source through a load and to transfer the ground return of the timing circuit from the junction of the coil and the capacitor directly to ground during the interval when the timing relay armature is closing to maintain the continuity of current flow; a load circuit including the coil of a pilot lamp relay connected across the source and switch through a third normally open set of timing relay contacts and thence through a load to ground; and a pilot lamp indicating circuit connected across the source and switch including a pilot lamp and a normally open set of pilot lamp relay contacts adapted to close upon operation of the pilot lamp relay.

9. The circuit defined in claim 8 in which the pilot lamp relay coil is adapted to operate with a multilamp load having a specified number of lamps and to be inoperative with a lamp load of one less than the specified number of lamps, whereby the pilot lamp indicates load lamp outage.

10. The circuit defined in claim 9 having a multilamp load for signalling a left turn, a multilamp load for signalling a right turn, a left turn pilot lamp, a right turn pilot lamp, and a turn signal switch for alternatively completing the circuit to the right or left signal lamp loads and simultaneously connecting the corresponding right or left pilot light in the pilot lamp indicating circuit.

11. The circuit defined in claim 10 having an emergency switch for disconnecting the circuits to the turn signal switch and connecting both the left turn signal lamp load and the right turn signal lamp load simultaneously into the load circuit, the emergency switch overriding the turn signal switch, for causing all the turn signal lamps to flash when the emergency switch is operated.

12. A vehicular lamp flasher and outage indicator circuit comprising: a transistor oscillator including a source of direct current and a switch in series; a transistor connected as an emitter follower with a timing relay coil in the emitter circuit; a charging circuit consisting of a first resistor connected to the transistor collector electrode, a second resistor, and a capacitor in series in that order connected across the transistor and relay coil, the junction of the second resistor and capacitor being connected to the base of the transistor, the junction of the first and second resistors being connected by a first set of normally open contacts on the timing relay to the junction of the coil and the capacitor; a plurality of lamp loads, a second set of make before break contacts on the timing relay arranged to normall connect the relay coil to the grounded side of the source through a load and to transfer the ground return of the timing circuit from the junction of the coil and the capacitor directly to ground during the interval when the timing relay armature is closing to maintain the continuity of current flow; a load circuit including the coil of pilot lamp relay normally connected across the source and switch through a normally closed pair of a third set of timing relay contacts and thence through one pole of a multiple pole emergency switch and one pole of a multipole turn signal switch and load to ground, the third set of contacts being adapted upon operation of the timing relay to transfer the load circuit through another pole of an emergency switch, and thence through another pole of the turn signal switch and another lamp load to ground; and a pilot lamp indicating circuit including a pilot lamp and a normally open set of pilot lamp relay contacts adapted to close upon opera tion of the pilot lamp relay for connecting the pilot lamp across the source and switch.

13. The circuit defined in claim 12 in which the pilot lamp relay coil is adjusted to operate with a multilamp load having a specified number of lamps and to be inoperative with a lamp load of less than the specified number of lamps, whereby the pilot lamp indicates load lamp outage.

14. The circuit defined in claim 13 having a first set of signal lamps on one side of the vehicle, a second set of signal lamps on the other side of the vehicle, the turn signal switch being adapted for connecting the first set of lamps in the load circuit through the normally closed pair of the third set of timing relay contacts through the emergency switch, and simultaneously connecting the second set of lamps in the load circuit through the third set of timing relay contacts when the timing relay is energized for alternate flashing, the emergency switch being adapted upon operation to break the connection through the normally closed pair of third set of timing relay contacts and to simultaneously connect both sets of lamps in the load circuit through the third set of timing relay contacts when the relay is energized for flashing all the signal lamps simultaneously.

15. The circuit as defined in claim 13 having a multilamp left turn signal load, a multilamp right turn signal load, a left turn pilot lamp, a right turn pilot lamp, and a double pole double throw alternating flasher switch; the emergency switch comprising a triple pole double throw switch having one pole normally closed and connected to one pole of the alternating flasher switch and operable to break this last named connection, the other two poles being operable to connect the right and left lamp signal loads, respectively, in the load circuit through the third set of timing relay contacts when the timing relay is energized for flashing all the signal lamps simultaneously; the alternate flasher switch being operable to connect one turn signal load in the load circuit to the normally closed pair of the third set of timing relay contacts through said normally closed pole of the emergency switch and simultaneously connect the other turn signal load in the load circuit to the normally open pair of the third set of timing relay contacts for alternately flashing both turn signal lamp loads; the turn signal switch being a double pole double throw switch adapted to alternatively connect the left or right turn signal load in the load circuit to the third set of timing relay contacts when the relay is energized and at the same time connect the left or right pilot lamp in the pilot lamp indicating circuit for flashing only one turn signal lamp load and its corresponding pilot lamp.

References Cited UNITED STATES PATENTS 3,113,242 12/1963 Leeder 315-209 3,263,123 7/1966 Leeder 315-209 JOHN W. HUCKERT, Primary Examiner.

R. F. POLISSACK, Assistant Examined. 

1. A LAMP FLASHER AND OUTRAGE INDICATOR CIRCUIT COMPRISING: A SOURCE OF DIRECT CURRENT HAVING ONE SIDE CONNECTED TO GROUND; A TRANSISTOR OSCILLATOR HAVING A VOLTAGE BUILD-UP CIRCUIT INCLUDING THE COLLECTOR AND EMITTER ELECTRODES OF A TRANSISTOR AND A TIMING DELAY COIL CONNECTED IN THAT ORDER TO THE SOURCE AND THROUGH A RETURN SWITCHING CIRCUIT TO GROUND; THE OSCILLATOR HAVING A CHARGING CIRCUIT INCLUDING FIRST RESISTANCE MEANS, SECOND RESISTANCE MEANS, AND A CAPACITOR CONNECTED IN SERIES ACROSS THE TRANSISTOR AND COIL, THE JUNCTION POINT OF THE SECOND RESISTANCE MEANS AND CAPACITOR BEING CONNECTED TO THE BASE ELECTRODE OF THE TRANSISTOR; THE TIMING RELAY HAVING A FIRST SET OF NORMALLY OPEN CONTACTS ADAPTED TO CLOSE UPON THE OPERATION OF THE RELAY TO CONNECT THE JUNCTION POINT OF THE FIRST AND SECOND RESISTANCE MEANS TO THE GROUND RETURN CIRCUIT; AND A SECOND SET OF DOUBLE THROW LOAD SWITCHING CONTACTS ON THE TIMING RELAY ADAPTED TO SWITCH SIGNAL LAMP LOADS ACROSS THE SOURCE ALTERNATELY THROUGH A FIRST SELECTED LAMP LOAD AND THEN THROUGH A SECOND SELECTED LAMP LOAD FOR ALTERNATING FLASHING OF THE LOADS. 